Moisture diffusion and shrinkage in heated air drying of potato and yam bean | |
| Author | Ganjyal, Girish |
| Call Number | AIT Thesis no.PH-00-11 |
| Subject(s) | Potatoes--Drying Potatoes--Moisture |
| Note | A thesis submitted in partial fulfillment of the requirements of the degree of Master of Engineering. |
| Publisher | Asian Institute of Technology |
| Abstract | Drying experiments were carried out in a fluidized bed drier to study the moisture transport properties of potato and yam bean as influenced by the shape and size of sample and drying air temperature. A total of fifty four tests were carried out using cubical and cylindrical shape of test sample and drying air temperatures of 50, 70 and 80°C. Diffusion coefficient, D, was determined for cube and cylindrical shapes using the one dimensional infinite series solutions for regular shape bodies, based on solution of Fick's law. For potato, the D value ranged between 630x10^-10 and 3.15x10^-09 m^2/s for cylinders and between 1.25x10^-09 and 2.95x10^-9 m^2/s for cubes. The D value ranged between 1.20x10^-09 - 2.55x10^-09 m^2/s for cylindrical sample for yam bean, while for cubes the range was from 7.90x10^-10 - 2.62x10^-09 m^2/s. Increase in air temperature led to an increase in D value, and the change in dimensions produced statistically significant difference, other conditions being kept constant. Diffusion was higher when the volume to surface area ratio was higher, causing D values to vary for different shapes. Based on multiple regression, models were developed for relating diffusivity of potato and yam bean, with temperature of drying air, volume to surface area ratio of samples. Simple and modified logarithmic drying models were also used to determine the drying constants, k and k' both for potato and yam bean, and related them with temperature of drying air and volume to surface area ratio of samples. The comparison of experimental and estimated values of moisture ratios both for potato and yam bean indicated that the modified log model approach was relatively better than diffusion coefficient determination. Shrinkage of the sample was studied determining the change in the volume and the density of the samples with the time of drying. The change in volume and moisture ratio were linearly related for the whole range of the drying curves. Similarly, the change in density of the samples were related to the changes in the moisture ratio, which increased initially to a optimum value and then decreased. There was no significant difference in the shrinkage of the samples for different drying air temperatures and shape and sizes of the sample. |
| Year | 2000 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Postharvest and Food Process Engineering (PH) |
| Chairperson(s) | Jindal, V. K. |
| Examination Committee(s) | Athapol Noomhorm;Rakshit S. K. |
| Scholarship Donor(s) | Queen Sirikit Environment Scholarship |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2000 |